OTOY Forums

I'm a bit confused about the materials terminology in Octane, being used to the properties in Lightwave and Modo.For example, in either program you can raise the specular property and see the effect on the material, which is kind of a fake reflection, even if it's not exactly that in theory. But it makes the surface looks less flat. Or, I can make a specular texture for it, or apply one from an object that I got from someone else, or that was in the Lightwave content for example. As you know, most objects usually come with a diffuse texture, a specular one and sometimes a bump one if not more.

The problem is that the Octane diffuse material doesn't have a specular input. It has a transmission input that I'm still not clear what it does. In the manual, all it says about it is this:

"Transmission: The Transmission value gives the base color to the mesh."

However, when I move its slider all it does is make the texture lighter as it reaches 100%.

The only material that has a specular input is the glossy material, but what if I just want specularity, not reflection? For example in the case of the grass in the LW content, which has a diffuse and a specular texture, if I use a glossy material and I connect the specular texture to the specular input, the result is grass that looks like is made of mirrors. So for grass I have to use the diffuse texture, but the blades look rather flat without its specular texture. How do I apply the specular texture of this or any object to an Octane shader?

Thanks

Diffuse Material - Matt, no shine or reflection.
Glossy material - has Specularity and roughness parameters (grass is glossy, so you need to play with these two inputs)
Specularity material - see through for glass or liquids.

You need to make sure your Specularity texture is low enough so that it's not mirror finish. And play with the roughness to get a good result. Index will help too. If there's a good grass material in LuveDB. Open it in standalone and look at the settings.

I find almost every texture I've used for Specularity in LW, I have to reduce in brightness for Octane. Eithe re turn down the first setting (can't remember if it's called level or amount it something. Or use a colour correct node to adjust it. I find having a spare diffuse material node that I PLG the texture into while I adjust it quite useful.

Perhaps you can see what I mean about the materials being totally different from lightwaave

Like Gordon says. Specular and Diffuse are totally different beasts from LW... zoinks! And keep in mind bro, without this type of unbiased physically-based render engine under the hood, folks like Newtek, Autodesk et al, have to completely fake all this crap in their rendering engines - and this is why LW has a Specular setting and a Reflection setting... It truly is all smoke and mirrors.

3Dimensional, I highly recommend hopping into standalone, dragging some materials out of LiveDB, double-clicking on them, and reverse engineering the shit out of some of the more complex Octane materials. A full day of this, way back when, made me whiz at Octane materials. It is time very well spent.

Thanks for your replies. The thing is that even if I can lower the white level in the specular texture and set the diffuse so it's not mirror-like, it will still have reflections, meaning that it will add rendering time, and I have a lot of grass. With the diffuse material it doesn't have any reflections, so in theory it shouldn't spend time on that, right?

The point of Octane is physical accuracy. Grass is not matt, it has a glossy surface. Glossy surfaces have reflections. If you lower the spec value, and increase the roughness value, those reflections will be more realistic. If you don't want any shine/glossiness to the grass, use a diffuse material.

You can also use the material mixer node to mix a diffuse material and a glossy material. Perhaps with this setup you could get what you are looking for.

-Juanjo

Make sure you set the IOR as well to get the Fresnel effect on the leaves.

Edit - tablet crapped out, here is the rest.

IOR is 1 by default, so reflectivity is the same across all viewing angles. I'm pretty sure leaves will have a falloff, so either set the IOR or use falloff node to control, unless you want metallic leaves! I render alot of plastics, so for example, normally set IOR of glossy material to ~ 1.5.

Thanks to all for your replies. I tried the material mixer and it looks a little better, but not enough to justify the extra time in rendering, so I set it back to diffuse only.

Sounds like a blurred reflection map would be perfect for this...

U have to use glossy material or a material mixer...ref juan
And think physical real world ior NB see this
http://render.otoy.com/manuals/Standalone/?page_id=344